Snap action electric switch with overload protection



July 14, 1953 R. c. INGWERSEN SNAP ACTION ELECTRIC SWITCH WITH OVERLOAO PROTECTION EIIed OCT. 24, 1951 WEI- l I C;

Il Il, I 36- FTI/2;- lZL Patented July 14, 1953 SNAP ACTION ELECTRIC SWITCH WITH OVERLOAD PROTECTION Richard C. Ingwcrsen, Jackson, Mich., assignor to MechanicalV Products, Inc., Jackson, Mich., a corporation of Michigan Applicationctobel 24, 1951, Serial N0. 252,9079

This invention relates to electric switches and more vparticularly to manually actuatable spring snap action switches which incorporate electrical overload protection. Y

It is an object of the invention to provide a snap action electric switch which is of compact and' efficient design and construction and with which the desired make and break connections take place with a well defined and positive action.

It is ia further object of the invention to provide a snap action electric switch with a thermal latch overload protection device which` is held firmly in operative position against unintentional or accidental actuation but is freed to move to open the controlled circuit the instant the thermal latch is subjected to the influence of a predetermined overload current.

It is yet another object of the invention to provide an electric switch assembly comprising movable contact means and a supporting structure therefor which when moved to engage the said contact means into engagement with cooperating iixed contact means energizes a spring finger assembly into retaining relationship with respect to an abutment structure in order to bias the movable contact means into the closed relation with respect to the iiXed contact means.

These and other objects and advantages of the invention, residing in the construction, arrangement and combination of parts will appear clear from consideration of the following description with reference to the drawings and from the appended claims.

In the drawings:

Fig. I is a side elevational view, partly in section, ofA one form of the invention showing the position of the parts in which athermal overload latch unit is held in the set operative position in which the controlled circuit contacts are closed, and is held biased into such position by the retaining action of ,a spring finger assembly incorporated in the switch structure,

Fig. II is a vertical end section of Fig. I,

Fig. III is a similar view to Fig. I; looking on the opposite side of the switch assembly, and

Fig. IV is a similar View to Fig. II..but with the thermal latchy shown moved to thev release position and the spring fingers at the instant of theirv outwardly deflected release position, upon the occurrence `of which the actuator plunger, carrying the spring fingers with it, moves immediately to the reset position.

Referring to the drawings, |0- indicates a casing havingk ahollow interior-in which ixed electrical contacts I2 are located in opposed relation Yto 9. Claims. (Cl. 200-116) movable electrical contacts I4, the latter.- being carried at the ends of spring arms I3vv secured` upon a block I8.- of insulating material, uponl which block there is also secured a. bimetallic thermal latch device, indicated generally at; 2,0;Y

This block i8 is mounted forV sliding movement upon actuator plunger 39, to be kdescribed later.

Rivets 2'2- may be employed to secure both the spring arms I3 and the thermal latchr device upon the insulated block I8..

The fixed contactsV l2.y are carried uponl conductor strips 24v guidedv in slots 26 in the casing lil and having terminal posts 28,0utside the casing.

The insulated blockv l 8 is guided upon an actuator plunger, indicated generally at 30, having integral fork portions 3i at one end and a pushpull button 33 ati its opposite end, rigidly connected with the plunger 3i), as by the securing pinV 35.

The push-pull button 33' is slida-bly guided in a bore portion 32 of an insulated block 34 ixedly secured upon the casing I0' and havingoppositely extending integral ears 36 and a guide slot 3.8 for accommodating the corresponding portion of the plunger 3G, shown as of bar formation but` upon opposite sides of a centrally located elon` gated block 50 secured upon the casing, as by the screw studs 52, and having, on opposite surfaces thereof, transverse depressions 54 (Fig. IV) of substantially V-section, serving as anchorages for Y snap action `spring fingers 56 secured upon the plunger 301forunitary motion therewith.

The spring iingers 56- are secured at one end thereof upon opposite sides of the plunger 3i), as by means of rivet 58, so as normally to deiiect outwards, as seen in Fig. IV, from engagement with the anchorages 54, this occurring when the thermal latch 20 is in the release position as shown in this figure. Each spring nger is in the form of a spring blade mounted upon the actuator plunger so as normally to spring outwards, as stated, and having'any inwardly bent transversely extending deiined V-portion 59 shaped and located to engage in the anchorages 54 when in the inwardly stressed condition, with the thermal latch in the latched position as seen in Figures I to III.

rIhe thermal latch 20 is of bimetallic construction and is mounted upon the insulator block IB so as to deiiect outwards (to the left as seen in Fig. II) under the inuence of increase in the temperature arising in the electrical circuit, this latch being connected in electrical series with the movable contacts I4. As seen in Fig. III the thermal latch is in the form of a U-shaped member and is mounted upon one side of the insulator block so that its base portion can engage an abutment ledge 65 provided in fixed relation upon the actuator plunger. The ends of the U-latch are bent back and secured across the top of the insulator block, upon opposite sides of the actuator plunger 3G, as by the rivets 22 aforementioned.

Coil springs 6I, secured between ears 62 on the slidable insulator block I8 and the ears 36 on the fixed insulator block 34, are stressed when the thermal latch 26 is engaged with the abutment ledge 60 and serve to urge the entire block and latch unit I3, 2S, together with the movable contacts I4, suddenly away from the fixed contacts I2, at the instant the latch 20 is moved from engagement with the abutment ledge 80.

Provision may be made to adjust the degree of engagement of the latch 20 with the abutment ledge 60 and thereby enable sensitive calibration to be effected after the switch components have been assembled and the switch is subjected to test, it being appreciated that the time of disengagement of the latch from its abutment ledge involves consideration of the distance the edge of the latch, in engagement with the abutment ledge 60, has to travel before the latch is free to be moved away from the ledge by the action of the springs 5 I. Such adjustment can be readily effected by manual adjustment, as with the use of a screw driver, by a screw stud 64 mounted upon the actuator plunger 30 in position to engage the latch 20, as seen in Fig. II,

and accessible for adjustment through an opening B5 in one side wall of the casing I0, such opening being normally sealed or closed, as by the screw plug 68, to prevent unauthorized tampering with the adjustment screw 64.

In operation, with the parts as seen in Figs. I-III, the contacts I4, I2 are held firmly closed, since in this position the spring ingers 56, stiffened by the presence of the now depressed block I8, are held rmly in Contact with the block 50 by engagement of their inwardly directed V-poitions 59 in the anchorages 54 on the block 50. At the same time thermal latch 20 is held latched against the abutment ledge GII, with the springs 6I stressed. Upon the latch 20 being subjected to the heat of overload current and thereby expanding outwardly from engagement with the abutment ledge 60, the springs Ill operate immediately to urge the block I8 and the movable contacts I4 away from the fixed contacts I2 with snap action. As this movement occurs the block I8 moves away from its encompassing relation with respect to the anchored end portions of the spring ngers 55 and thereby frees these fingers to spring outwards from their previously stressed enga-gement with the anchorages 54. The actuator spring 42 is stronger than these untensioned spring fingers 55 so, if freed, will immediately urge the plunger outwardly to the dotted and reset position as seen in Fig. III.

Even if the plunger is held depressed this cannot prevent the thermal latch action from taking place, which does so with trip-free effect, as will be appreciated. The plunger must, of course, be released to permit resetting of the latch after release.

Upon the latch being reset against the abutment ledge 60 the spring fingers 56 will again be stressed inwards by the again encompassing block I8, so that the free end portions of these iingers, containing the deiined portions 59 must be forced past the ends of the block 50 and engaged in the anchorages 54 by cam action, as will be appreciated. This cam action is attended s with a final snapping of the finger portions 59 into the anchorages 54, the result of which is to urge the movable contacts in the direction of the iixed contacts I2 to thereby maintain a irm contact making relationship.

While the invention has been described with reference to one particular embodiment it is to be understood that the actual construction involved is capable of modification to meet particular requirements and practical considerations, such as falls within the spirit and scope of the appended claims.

Having thus described the invention, what I claim as novel and wish to secure by Letters Patent is as follows:

1. In an electric switch assembly, casing structure, fixed contact means in said casing structure, movable contact means positioned in said casing structure for engagement with said xed contact means spring means connected with said movable contact means so as to be tensioned when the movable contact means are moved into engagement with the xed contact means, actuator means connected with said movable contact means and mounted on said casing for movement to engage said movable contact means with said xed Contact means and tension said spring means, said tensioned spring means being operative to restore the movable Contact means to the contact open position upon release from engagement with the fixed contact means, and separate spring means actuated by said actuator means to bias the movable contact means into contact making relation with respect to said fixed contact means upon movement of said actuator means to engage the contacts.

2. An electric switch assembly as claimed in claim l, said separate spring means being carried by the actuator means, and anchorage means on said casing for engagement by said separate spring means to effect said bias.

3. An electric switch assembly as claimed in claim 1, said actuator means comprising a plunger, said plunger being slidably mounted on said casing structure and said movable contact means being carried upon said plunger, said casing structure including fixed anchorage means said separate spring means being of spring blade form having a defined portion for engagement with said anchorage means with a cam action which gives rise to said bias action.

4. In an electric switch assembly, casing structure, iixed contact means in said casing structure, movable contact means positioned in said casing structure for engagement with said fixed contact means, actuator means connected with said movable contact means and mounted on said casing for movement to engage said movable contact means with said iixed contact means. spring means connected to be energized by movement of said actuator means to engage said contact means and operable to move said movable contact means to open position, and separate spring means actuated by said actuator means to bias the movable cont-act means into contact making relation with respect to said xed contact means upon movement of said actuator means to engage the contacts.

5. An electric switch assembly as claimed in claim 4, said actuator means being movable manually to close the contacts, and spring means for restoring the actuator means to the open contact position.

6. In an electric switch assembly, casing structure, xed contact means in said casing structure, movable contact means positioned in said casing structure for engagement with said xed contact means, actuator means connected with said movable contact means and mounted on said casing for movement to engage said movable contact means with said fixed contact means, means mounting said movable contact means on said actuator means for movement relatively thereto, latch means for releasably latching said movable contact mounting means in set position on said actuator means for making contact With the fixed contact means when the actuator means is actuated to engage and close the contacts, spring means connected to be energized when said movable contact mounting means is latched in said set position, whereby said mounting means and rthe movable contact means carried thereby is moved relatively to the actuator means in the contact opening direction by the resulting spring action upon said latched setting being broken, separate spring means actuated by said actuator means to engage said separate spring means with said fixed anchorage means and thereby bias the movable contact means into contact making relation with respect to said xed contact means upon movement of said actuator means to engage the contacts.

7. In an electric switch assembly, casing structure, Xed contact means in said casing structure, movable contact means positioned in said casing structure for engagement with said fixed contact means, actuator means connected with said movable contact means and mounted on said casing for movement to engage said movable contact means with said xed contact means, frame structure upon which said movable contact means is secured, said frame structure being slidable upon said actuator means for movement relatively thereto, said actuator means Ihaving an abutment for the engagement of said frame structure to position the movable contacts for movement with the actuator means in the contact closing direction, spring means connected to be energized when said frame structure is engaged with said abutment and operable to move the frame structure inthe contact opening direction upon disengagement of the frame structure from said abutment, and means actuated by said actuator means to bias the movable contact means into contact making relation with respect to said fixed contact means upon movement of said actuator means to engage the contact, said biasing means comprising spring means carried upon said actuator means and relatively fixed anchorages for said spring means, said frame structure being mounted on said actuator means to tension said spring means when said frame structure is engaged with said abutment whereby to constrain said spring means to engage said anchorages when the actuator is actuated to move the movable contact means into engagement with said fixed contact means, said biasing spring means being freed from said anchorages when said frame structure is disengaged from said abutment.

8. An electric switch assembly as claimed in cl'aim 7, said biasing means comprising spring means carried by said actuator means and having a defined portion thereon and abutment means with which said defined spring portion engaged with cam action to hold the movable contact means firmly against the xed contact means.

9. In an electric switch assembly having overload protection, casing structure, xed contact means in said casing structure, movable contact means positioned in said casing structure for engagement with said xed contact means, actuator means connected with said movable contact means and mounted on said casing for movement to engage said movable contact means with said xed contact means, frame structure carrying said movable contact means and a thermally responsive latch member, said frame structure being slidably mounted on said actuator means and said actuator means having :an abutment engageable by said latch member tol hold the movable contact in position to be moved by the actuator means into contact with the fixed contact means, said latch member being responsive to the current W for disengagement from said abutment upon the occurrence of a predetermined electrical overload, spring means connected to be energized when said latch member is engaged with said abutment to urge the movable contact means to open position when the latch member is disengaged from the abutment, and means actuated by said actuator means to bias the movable contact means into contact making relation with respect to said fixed contact means upon movement of said actuator means to-y engage the contacts.

RICHARD C. INGWERSEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,255,330 Platz Sept. 9, 1941 2,438,186 Randall Mar. 23, 1948 2,458,807 Tucker Jan. 11, 1949 2,485,736 Ingwersen Oct. 25, 1949 

